It takes Tom Meighan literally 90 seconds to mention Kasabian's public image. The singer shakes hands, orders a round of drinks and he's off: "People think we're lad rock. People think we're rowdy guzzlers, man. Beer guzzlers." It doesn't normally bother him, he says, but he had a recent encounter with a journalist who suggested that, given their beery, blokey, football-crowd following - the kind of fans Kasabian guitarist Sergio Pizzorno once proudly characterised as "people who would fight in a car park over you" - it was unwise for Meighan to wear his Paul Smith union flag shirt on stage. He brought up the unwelcome spectre of the furore Morrissey caused waving a union flag about supporting Madness in the early 1990s. Meighan was hugely offended. "He was going on about Morrissey being perceived as rightwing and I was like, 'Fuck off! Me dad's an Irish Catholic, so you're wrong there.' I wore the shirt because it represents the Who, Keith Moon, Pete Townshend, the Pistols, all the great things that have come out of Britain, Noel Gallagher with his union jack guitar. It's not a fucking Glasgow Rangers thing. He perceived us so wrong. It's horrible, I was really pissed off. Fuck you, pal!"

All this comes out virtually without a pause for breath. "How do you know our fans are like that? Just 'cos you assume it's lad rock, you think we're associated with the right wing? It's disgusting. We're not anything to do with that. Fucking hell!" he huffs.

Maybe the journalist was just trying to wind him up, he says, but it's been playing on his mind. He's had a lot of time to think recently. He has spent the past month away from his hometown of Leicester while Kasabian promote their third album, West Ryder Pauper Lunatic Asylum. He is, he says, "living like Alan fucking Partridge", although his upscale London hotel is noticeably more salubrious than the DJ's Linton Travel Tavern. In the time-honoured rock star tradition, he's booked in under a false name, Edgar Froese, after the head honcho of the German synth pioneers Tangerine Dream, a choice that indicates where his music tastes lie. He's currently much enamoured of the odder end of British prog: "The Moody Blues, man! And Egg! Fantastic!" he enthuses.

That's not a sentence that's ever going to pass the lips of Meighan's friend Liam Gallagher, the frontman to whom he is most compared, nor indeed any other artist who attracts the lad rock tag. Nevertheless, you can detect a taste for the esoteric in Kasabian's music. The current single, Fire, sounds pretty improbable among the rest of the Radio 1 playlist, with its sudden lurches in mood and tempo and rhythm. Meighan describes it as flipping out; if the song were a person, he would be nice, "then he's got a hammer in his hand the next minute". Their new album is tipped not just to replicate, but improve upon the platinum success of its two predecessors, 2004's eponymous debut and 2006's Empire. It bears the influence of DJ Shadow (it's co-produced by occasional Shadow and Gorillaz collaborator Dan the Automator), late-60s electronic pioneers the Silver Apples, and a variety of krautrockers, or as Meighan colourfully puts it, "those, German experimental bands dressed up as fucking wizards and kings". "We've put drum'n'bass with guitar over the top of it and called it Swarfiga, man," he says. "I'd expect someone like Radiohead to do that. Fucking serious. That's something Thom Yorke would do."

But no one would ever mention Kasabian in the same breath as Radiohead, although their music has always been a bit weirder than the bands their fans tend to like. They're named after Linda Kasabian, the Manson family's getaway driver turned star witness at the Tate-LaBianca murder trial. They spent two years living "like a cult" on a communal farm outside Leicester. On the cover of West Ryder Pauper Lunatic Asylum they appear in fancy dress: Meighan as Napoleon, Pizzorno as a priest. Before Britpop, Pizzorno began his musical career gamely attempting to make his own rave tracks on a cheap sampler, and something of the dancefloor has always stuck to their sound. "I was too young to have gone to a hardcore rave, but I had this image in my head: you got tapes passed around the class, you heard they got busted by the police, it seemed like an exciting scene. Then Britpop came along and that's why I bought a guitar. When I kind of combined the two things, that was the start of Kasabian." They protest vigorously about being compared to the Happy Mondays - "We sound fuck-all like them" - but you could argue that's exactly whom they most recall, at least in the sense that their weirdness and experimentalism and love of Can gets overlooked in the face of their popularity and geezer appeal.

Part of the problem, Meighan thinks, might be to do with the improbable collision of Kasabian's more outre influences with a certain earthiness born out of their geographical roots. "Bands from the Midlands, they've got this sort of balls-out thing - there's this DNA of really loud fucking bands. Black Sabbath, Led Zeppelin, Slade. It breeds absolute fucking monsters."

Pizzorno thinks the Midlands may have had another, more prosaic effect on people's perception of the band. "You're right," he nods sadly. "I think people do think we're thick. Our accents don't do us any favours. People don't seem to realise that we're taking the piss. Our first single was called Club Foot. No one seemed to see the funny side of that."

Both may have a point, although in fairness, you are perhaps asking for people to overlook both your subtle wit and your experimental musical tendencies if you insist on being introduced on stage at the Royal Albert Hall by Gordon Smart of the Sun. Pizzorno says it doesn't matter anyway. "The perception of our band's quite funny, but it all adds to the mystique. I don't mind pissing people off. I think that's part of your job. I think it makes us more psychedelic. It's almost twice as psychedelic because it comes from us."

Arriving one after the other in a north London pub, Meighan and Pizzorno offer an intriguing study in contrasts. Meighan demolishes a couple of vodka and tonics, Pizzorno sips at a can of Coke. Meighan thinks West Ryder Pauper Lunatic Asylum is a concept album, about "this fucking mental institution with different characters in it for different songs". Pizzorno - who wrote all the music and lyrics - looks a bit wary of the description: "I don't want to get too weighed down in having a story. It's not Tommy. You can smoke too much weed and start making up imaginary characters for each song, but ultimately we just wanted to have 12 great songs on it."

And while Pizzorno is thoughtful and softly spoken, Meighan's answers tumble forth in a wild, animated tangle of superlatives, expletives, malapropisms and hilarious anecdotes, many of which seem to bear only the most distant relationship to the question he has been asked. He often contradicts himself ("We haven't had any hits," he offers, before reconsidering: "Actually, we've had a few hits") and occasionally his answers veer so wildly off-piste that he feels impelled to offer advice on how I might edit them into some kind of readable feature: "I've skipped on to a different subject," he says, when he finds himself talking about what he recently bought in Selfridges' menswear department, ostensibly in answer to a question about the band's musical influences. "You can use that in a different bit of the article, or you needn't use it at all. It's up to you."

Meighan is wildly, puppyishly enthusiastic about the new album. "I've bored my next-door neighbour half to death with it, and my missus. If people like it half as much as I do, then I've won, because I fucking love it." But then, he's wildly, puppyishly enthusiastic about pretty much everything, including Ramsay's Kitchen Nightmares ("He's a fucking monster, Ramsay") and Leicester's indoor market. "It's one of the best in England. I just go down there and walk around, buy dragon fruit, the missus likes it. It's got bread stalls, cake stalls, stalls that sell all PlayStation and Nintendo games, lovely cheese, brilliant fish. Great market, man."

For all his self-belief and bravado, his is unmistakably the zeal of someone who can't quite believe his luck, who still has some difficulty working out exactly how a chance teenage meeting with Pizzorno in a Leicester park - he can't remember whether he was drunk or "just being me", but he was singing and the guitarist overheard him - led to a couple of million album sales and selling out Earl's Court. "I wake up every morning and think, 'Wow, what a fucking great life.' We're making music and people give a shit, you know? I love being Tom Meighan." He is slightly exhausting company - "I am a little bit hyper," he notes, a master of understatement - but it would take an almost superhuman effort to dislike him.

Pizzorno, meanwhile, quotes Charles Bukowski, discusses Stanley Kubrick and Ennio Morricone and enthuses over the experimental films of Alejandro Jodorowsky. All this seems rather at odds with his public image, which is big on a gobby, macho braggadocio of the best-band-in-the-world variety; it was Pizzorno who put about the rumour that Keane singer Tom Chaplin's stint in the Priory was the result of an addiction to port. "When it's written down, it always looks worse than it is," he says with a smile. "But if you're taking a circus out, you've got to sell the tickets. There's a lot of circuses out there and yours has got to stand out."

Perhaps it has something to do with his teenage years, during which he attended a school where "if you played guitar you got beat up for being a ponce", followed by a period as a trialist for Nottingham Forest. "It hardens you up, you're graded, you're under the spotlight. With football, you've got to stand up for yourself or else you get trampled on among the other lads. If you seem to be weak in any way, you can get stamped on."

You can see how Meighan and Pizzorno's different characters affect the band. Like his conversation, Meighan's performance style is cheeringly intuitive and unaffected, as demonstrated to a global audience a couple of years ago when he took the stage at Live Earth and added his own unique, bellowed contribution to the day's earnest speechifying about CO2 emissions: "Let's try and ... save the polar bears, yeah?" Meanwhile, it was presumably Pizzorno rather than Meighan who came up with the idea of sampling Sans Soleil, the 1983 "essay film" by the French director Chris Marker, on the album's title track: more evidence that, whatever you think of Kasabian and their fans, at least you could never accuse the former of underestimating the latter. "I think what's exciting about our band is that we get geezers at our shows, but we're not really giving them geezer music," says Pizzorno.

Still, he concedes, it's a job that comes with risks: not least that the geezers are going to take one look at West Ryder Pauper Lunatic Asylum's cover and opt instead for a band who don't think it's a good idea to dress up as Napoleon. "There's a lot of times when I look at the album cover and think, 'Fucking hell, this is going to bomb.' If people don't get it, it's going to be like ... " He shrugs. "Still, it's going to be a beautiful explosion."